Since the early 1950's, the various branches of the United States Department of Defense (DOD) and the United States Department of Energy (DOE) have been aggressively developing and manufacturing nuclear weapons and energy components involving various radioactive materials. The process of refining nuclear materials and decontaminating various apparatus used in these processes and others with various types of organic and inorganic materials has generated hundreds of thousands of tons of soils, sludges, debris or other residuals contaminated with radionuclides and various hazardous and non-hazardous organic and inorganic chemical constituents. The United States Environmental Protection Agency (EPA) has defined a waste that contains radionuclides and hazardous or non-hazardous waste constituents as a mixed waste.
Historically, mixed waste was typically stored on site in containers in designed containment areas, or storage vessels or disposed of in landfill cells or trenches. The disposal of mixed waste in DOD or DOE landfills or trenches is no longer permitted. Due to the promulgation of EPA regulations, mixed waste is not permitted to be disposed of at an EPA approved hazardous waste facility or a radioactive waste facility until the constituents can be separated and segregated from each other.
This need to remediate the mixed waste at these sites is being accelerated due to the fact that the DOE and DOD are currently undergoing a major restructuring effort, whereas numerous DOE and DOD facilities throughout the country are being decommissioned and decontaminated for light industrial, commercial or residential redevelopment. A large percentage of these facilities contain soil, sludges or other residuals, which is defined by the EPA as a mixed waste. To compound the problem, the mixed waste that has been buried in trenches and landfills has had a significant impact on groundwater reserves in some locations. These areas must be remediated in accordance with EPA regulations which involves in most cases the removal and remediation of the pollution source materials (non-liquid matrices).
The present invention discloses a method that is capable of separating hazardous and non-hazardous organic and inorganic constituents from the non-liquid matrices without destabilizing or spreading the radionuclides. After separation, the radioactive waste stream is either disposed of at the DOE or DOD facility in accordance with EPA regulations, or disposed of at an EPA approved radioactive waste facility. This allows for a significant economic benefit to handle this waste stream in this manner. Currently, there are virtually no available methods to conduct the separation of this waste stream in an environmentally sound and cost effective manner.
In addition to mixed waste, the annual generation of hazardous and non-hazardous (chemically contaminated) wastes in the United States alone is estimated to be in the range of hundreds of millions of metric tons. Industries throughout the world rely on processes in manufacturing which generate waste products routinely. Many of these waste products are disposed of as hazardous waste, which is very expensive. There is a need to reclaim for reuse some of the raw materials by separating the contaminants from various matrices. This allows industry to minimize the waste that is produced, lower operating costs and comply with current regulations.
The hazards to public health and the environment, which are posed by these various chemical constituents, are well known and documented. Various methods for the destruction or decomposition of high boiling point hazardous wastes is extremely expensive. It is not very cost effective to utilize high grade energy to thermally destroy an entire hazardous waste matrices when the contaminant itself is such a small portion of the volume by weight. Also, because the non-liquid matrix which has become contaminated due to contact with the chemical compound should be reused or recycled if possible. It is more cost effective with regard to matrices contaminated with hazardous wastes such as PCBs, pesticides, herbicides, PCPs, dioxins, furans, and the like to minimize the waste stream which require expensive destruction or decomposition methods by separating the bulky non-liquid matrix which typically makes up between 75% to 90% of the waste stream volume.
Therefore, the invention provides an economical waste minimization and resource recycling method as an alternative option to the current art in response to a market need for technology to better handle industrial process waste, mixed waste and hazardous waste streams in an environmentally sound and cost effective manner. O'Ham (U.S. Pat. No. 5,127,343, the entire contents of which are herein incorporated by reference) teaches an apparatus and method for decontaminating and sanitizing soil, particularly soil containing petroleum hydrocarbons, such as gasolines, oils, and the like in a batch process where the soil is stationary during treatment. This process was specifically designed in response to the large market need for on-site treatment technology of petroleum hydrocarbon contaminated soils from gasoline service stations and other related users of petroleum products, in response to the regulatory requirements of the Underground Storage of Hazardous Substances Act and related regulations, which required petroleum hydrocarbon contaminated soils to be remediated.
The prior art has no means of controlling fugitive dust during the loading and unloading of matrices. Soil is normally transported via loader from a stockpile to the processing device. In doing so the contaminants are spread through spillage and wind born dust. Both workers and possible bystanders, or nearby public have a much higher potential exposure to contaminants as well as possible uncontrolled releases of contaminants to the environment The prior art requires 20% and greater downtime to perform maintenance of the processor. Soils are placed directly into a process unit on screens (vacuum tubes) surrounded by a filter media (pea stone). Screens become easily plugged requiring constant cleaning between batches. The entrance door is lowered to allow for a front end loader to enter the chamber and deposit the soils for treatment and raised to create a track for the carriage of heaters to roll on top of the chamber for treatment. The entrance door hinges become blocked with matrices and filter media and have to be cleaned after each batch. These doors become easily damaged from this process and become nearly impossible to seal with air by passing the soil, resulting in insufficient treatment. Furthermore, damage to the hinge results in the access door becoming out of line. When this happens, the track for the heater carriage becomes out of line and can cause the heater carriage to fall off of the track on this side of the unit resulting in increased downtime.
Prior art was unreliable in treatment. Air flows through the static bed are uneven and variable resulting in temperature gradients across the matrix to be treated. Air bypasses were caused by plugged screens and pea stone, and the inability to seal the loading door. Also, the vacuum screens were located directly under only approximately 50% of the static soil bed surface area, resulting in incomplete treatment throughout the soil or creating “cold spots”. Uneven heating results in inadequate treatment.
The prior art uses expensive filter media which adds to the waste stockpile and cost to operate.
The prior art requires extensive cleaning between jobs. Often decontamination procedures are unsuccessful. This is due to the matrix placement directly within the treatment chamber. The matrices are forced into hard to access areas of the apparatus.
The prior art entrains dust particles and deposits them into the emission control system, restricting air flows and causing excessive maintenance requirements.
Prior art only allows for the treatment of hydrocarbons.
Prior art is only applicable to removal of hydrocarbons through thermal processes. The review of the prior art indicates that the art is limited to the removal of hydrocarbons from soils and is not suitable, with regards to economical, ecological and safety matters, for the treatment of various volatile organic and inorganic chemicals and high boiling point chemicals. Therefore, a need exists for an economical and environmentally friendly method that separates volatile organic and inorganic contaminants from non-liquid matrices and collects these contaminants for recycling or reuse. A need also exists for a system which allows for the reuse of the decontaminated non-liquid matrices. This method provides a social benefit by providing an ecologically sound solution for the minimization of waste streams in an economical manner.